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Adam Jointer usage
August 29th, 2005 01:35 AM
August 28, 2005 Jointer Usage


I don‛t know what your level of power woodworking experience you have (although first big project has been mentioned).

So... Here goes.

The jointer knives need to be set parallel with the bed and have equal extension (even with the out-feed table).

There are many different techniques and jigs that can be used to accomplish the above.

You sound very accuracy oriented. Most woodworkers deal with fractions of an inch (1/16, 1/32 & 1/64). Your use of thousands of an inch, coupled with a caliper, sounds like you might like the following article.

Checkout issue 165 of the October 2005 Better Homes and Gardens "WOOD" magazine has an appropriate two page article that makes use of a dial indicator and a special wooden jig the reader makes to set jointer knives.

The dial indicator is a simple 0 to 1 inch reading, 0.001 graduated, back lug mounted model.

Sears sells an Empire 2788 (Sears model 40777) indicator for around 25 or 30 bucks.

This same indicator (with appropriate holder) can also be used to measure run-out, end-play (thrust) and verify parallelity.

The jointer fence also has to be set at precisely 90 degrees. Don‛t rely on any machine stops. Always verify with a precision machinist‛s quality square.

Only the first jointed surface is jointed directly down against the bed. Afer establishing this one flat and straight surface, you can go on to establish square 90 degree corners.

When jointing the next two surfaces of your work piece, you need to reference the work against the precision adjusted fence and then downward. This is what gets the "square angle".

Flip the workpiece over and, using the same reference surface, joint the other side square with it.

Theoretically, you can now use either freshly jointed surface (against the fence) to joint the last surface.

With the knives adjusted even and level with the bed (out feed - left table) and the fence adjusted precisely to 90 degrees, you should obtain desired results.

Now for the "cupping" over the length of the board. The table top jointer has a shorter length bed for referencing against your work piece. It is not going to correct a long, gradual arc.

This is analogous to using a 9 inch long smoothing plane to "joint" an edge by hand. It wont cut it.

The 14 inch Jack or preferably a 22 inch Try plane has a longer sole that will ignore hills and valleys, producing a truly straight jointed edge.

You can still use the bench top jointer to good advantage on long pieces.

You will need a continuous straight edge (moving a short one is obviously not going to work).

A good commercially available product are the aluminum rules.

Sears sells several different lengths.

If your board is cupped downward (light under the middle of the straight edge), take a hand plane and "knock-off" some of the end wood on your board.

If the rule is a rocking, knock down that hill.

Don‛t worry about doing a perfect job. The board just needs to be straight enough for your jointer to accurately finish off.

Wood has a grain direction to it. Planing (power or by hand) can either be a pleasant experience or things can get nasty when going against the grain.

Make sure you take advantage of every safety device you‛ve got or can make or purchase. Jointers are very unforgiving when accidents are involved.

I still have nightmares of when my "highschool" wood shop teacher related the story of the adult school gentleman who couldn‛t wait for machine use instructions and proceed to attempt jointing a 10 inch long workpiece. It flew off the table and all FOUR of his fingers fell into the rotating blades!

Don‛t avoid your power tools. Just recognize their power and utter indifference to operator ignorance, fatigue or "experience".

I hope this is enough help for your jointer operations.

Have fun!
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